The present invention relates to a seatbelt device of a vehicle.
Conventionally, a rear seat for three passengers which is arranged in back of a driver's seat and has a center seat at its central portion is known.
A seatbelt device which can restrain the seated passenger to protect the passenger's protection against a vehicle crash impact is provided for each seat. In these days, it is legally required to provide the seatbelt device for passengers who are seated in the rear seat as well. Herein, a so-called three-point type of seatbelt is preferably applied to the above-described center seat of the rear seat from the safety viewpoints.
In this three-point type of seatbelt for the center seat of the rear seat, a belt body which is withdrawn from a retractor extends through a belt anchor which is arranged at a vehicle upper position, a tongue for anchor which is arranged at a tip of the belt body is operated so as to engage with a buckle for anchor which is arranged on one side of the seat, and a tongue for passenger restraint which is arranged so as to move along the belt body is operated so as to engage with a buckle for passenger restraint which is arranged on the other side of the seat. Thus, the seated passenger can be properly restrained by the three-point type of seatbelt.
Herein, the above-described rear seat has also both-sides seats for two passengers to be seated on both sides of the center seat. Accordingly, a retractor of the seatbelt device for the center seat may not be arranged inside a pillar of the vehicle, unlike the seatbelt device for the both-side seats. Thus, there may be a question of where the seatbelt device including the retractor for the center seat should be arranged. While the seat structure in which the seatbelt device is arranged at the seat itself has been proposed, this may require a design change and also cause a new problem in that the total weight and manufacturing costs of the seat would increase for necessary measures against the crash impact load.
Japanese Patent Laid-Open Publication No. 11-240415 proposes the structure in which the belt body withdrawn from the retractor which is arranged at the lift gate extends through the belt anchor which is arranged at the upper portion of the seatback, i.e., a so-called shoulder portion of the seat, the tongue for anchor which is arranged at the tip of the belt body is operated so as to engage with the buckle for anchor which is arranged on one side of the seat, and the tongue for passenger restraint which is arranged so as to move along the belt body is operated so as to engage with the buckle for passenger restraint which is arranged on the other side of the seat. According to the structure of this publication, it can be prevented that a large load acts on a connecting portion of the seatback and the seat cushion, and the support strength of the retractor can be increased.
Japanese Utility Model Laid-Open Publication No. 63-70461 proposes the structure in which the hinge reinforcement which is provided at the rear header at the rear edge portion of the vehicle roof supports the belt anchor for the rear seat. According to the structure of this publication, the three-point type of seatbelt for the center seat of the rear seat can be provided without any improper design change of the seat.
Meanwhile, in order to absorb the crash impact properly, the slant angle of the seatbelt between the belt anchor and the passenger's shoulder contact portion relative to the vertical direction, when viewed from the vehicle side, may be necessary to be large enough to protect the passenger properly. Then, in order to ensure this slant angle, it may be required that the belt anchor having the large support strength be arranged at a position which is located in back of the passenger, or the seatbelt device itself which comprises the belt anchor and the retractor be arranged at a position which is located in back of the passenger.
According to the structure of the above-described former publication, since the retractor is arranged at the lift gate, the seatbelt device can absorb the crash impact properly without any improper influence to the support strength of the belt anchor arranged at the shoulder portion of the seatback. However, since the retractor is arranged at the lift gate, the belt body extends from the retractor arranged at the lift gate to the seat equipped with the belt anchor arranged thereat when the seatbelt is applied. Accordingly, there is a problem in that the baggage space would not be used properly.
Considering the above-described problem, it may be considered that the retractor is arranged at the roof or the like so that it can be located at a position in front of the rear seat. In this case, however, it may be required that the support strength of the belt anchor arranged at the upper portion of the seatback be increased so that the crash impact can be properly absorbed, and the structure change of the seat itself, including reinforcing the connecting portion between the seatback and the seat cushion and the support strength of the belt anchor itself, may be necessary.
Meanwhile, the structure with the belt anchor arranged at the rear header at the rear edge portion of the vehicle roof in the above-described latter publication may be effective in reinforcing the support strength of the belt anchor regardless of the position of the retractor. In this case, however, if the vehicle's rear face is designed to be considerably inclined from vehicle's design requirements, the rear header may be positioned just above the seatback, so that there is a case in which the properly large slant angle could not be ensured even in case of the belt anchor being arranged at the rear header (see FIG. 15).